1)  flutter boundary

1.
A new method,roubust flutter margin method,of determining flutter boundary is introduced.

2.
Pass to incorporate organically the flight test data and the system model, make use of the structured singular value theories proceed the flutter boundary estimate.

2)  flutter boundary prediction

3)  Flutter Boundary Prediction (FBP)

4)  real-time flutter boundary prediction system

1.
The real-time flutter boundary prediction system predicts the critical speed of flutter during the course of airplane′s flutter test.

5)  flutter critical wind speed

1.
The results show that the flutter critical wind speed can be significantly increased by mounting an upper central stabilizing barrier on the top surface of the upper chords of the transverse frames of the truss girder,and the flutter .

2.
The variation pattern between flutter critical wind speed of bridge with flat box deck and wind yaw angle is significantly affected by wind attack angle.

3.
Thus the flutter critical wind speeds are much lower and the bridge is more unstable during this period.

6)  critical flutter velocity

1.
Numerical simulations for aerodynamic derivatives and critical flutter velocity of bridge deck;

2.
With the span of long-span bridges is becoming longer, the stiffness and damping ratio of structures decrease clearly and then critical flutter velocity falls accordingly.

 颤振flutter   弹性结构在均匀气（或液）流中受到空气（或液体)动力、弹性力和惯性力的耦合作用而发生的大幅度振动。它可使飞行器结构破坏，建筑物和桥梁倒塌。发生颤振的必要条件是：结构上的瞬时流体动力与弹性位移之间有相位差，因而使振动的结构有可能从气（或液）流中吸取能量而扩大振幅。最常见的颤振发生在机翼上。当机翼受扰动向上偏离平衡位置后，弹性恢复力使它向下方平衡位置运动，同时产生作用于机翼重心的向上惯性力，因机翼重心在扭心之后，惯性力产生对扭心的力矩而使机翼迎角减小，引起向下的附加气动力，加快机翼向下运动；当机翼运动到下方极限位置而返回向上运动后，出现相反的情况。整个过程中，空气动力是激振力，与飞行速度的二次方成正比；同时还有空气对机翼的阻尼力，与飞行速度成正比。低速时，阻尼力占优势，扰动后的振动逐渐消失，平衡位置是稳定的。当飞行速度超过颤振临界速度后，激振力占优势，平衡位置失稳，产生大幅度振动，导致机翼在很短时间内破坏。防止机翼颤振的最有效方法是使机翼重心前移以减小惯性力矩。设计飞机时，要在风洞中进行模型试验以确定颤振临界速度。飞机研制成功后，还需进行飞行颤振试验。